Security procedures are sometimes necessary to secure access and/or resources. In some instances, access to those secure areas or resources is conditioned on possession of secret information, such as a key. Thus, when a machine, such as a card reader securing a door reads a card or device inserted by a visitor, the machine reads the key from the card, does some processing and/or data look-up, and based on that determines whether to issue an “access grant” signal. A possessor of a validated key would be granted access, while others (presumably unauthorized visitors) would not be granted access. The access can be physical access to secured locations, access to data that is secured, or some other access.
Such security procedures should be not too complex, but should be reliable, versatile, and should operate with low delays.